From mboxrd@z Thu Jan  1 00:00:00 1970
From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Subject: Re: Oops with spin_lock() in an IRQF_NO_THREAD interrupt
Date: Fri, 4 Oct 2013 14:42:58 +0200
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To: Matthias Klein <matthias.klein@optimeas.de>
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* Matthias Klein | 2013-10-02 14:54:00 [+0000]:

>Hello,
Hi,

>i am writing a kernel module on a rt kernel where I have an
>IRQF_NO_THREAD interrupt.
I hope you know what you are doing with this.

>For sharing a "write index" between that interrupt and the process
>context (ioctl() etc.) I use a spin_lock for locking.
>
>In the IRQ I use spin_lock() & spin_unlock(), and in the process
>context I use spin_lock_irq() & spin_unlock_irq().
>
>Basically the driver and the test application are working, but after
>some time I get an oops message.
>
>Do I use the right functions for locking ? Do you have a tip why I
>get that oops message ?

You should use a the raw_spinlock here if you _really_ need
IRQF_NO_THREAD.

>Best regards,
>
>Matthias

Sebastian